#include <iostream>
#include <vector>
#include <cctype>
#include <algorithm>
using namespace std;

//97.42 %
class Solution
{
  public:
    string reverseString(string s)
    {
        int l = 0, r = s.size() - 1;
        while (l < r)
            swap(s[l++], s[r--]);
        return s;
    }
};

int main()
{
    string s = "A man, a plan, a canal: Panama";
    cout << Solution().reverseString(s) << endl;
    return 0;
}
